1. Field of the Invention
The present invention relates to a head actuator in which a magnetic head is attached to a rotatable arm by way of an elastic member, a hard disk apparatus equipped with a head actuator, as well as a method of manufacturing a head actuator. More particularly, the present invention seeks to provide a thinner head actuator, and thus a thinner hard disk apparatus, by way of a configuration in which two elastic members are attached to an arm in such a manner that the arm is positioned between the elastic members.
2. Description of the Related Art
FIGS. 11A and 11B are plan views showing configuration examples of conventional hard disk apparatuses (HDDs), where FIG. 11A shows a fixed hard disk apparatus and FIG. 11B shows a removable hard disk apparatus. In a conventional hard disk apparatus 51, magnetic heads 53 for recording and reading information on a disk 52, suspensions 54 for supporting these magnetic heads 53 on one end, and a head actuator 56 including an arm 55 for keeping these suspensions 54 fixed in place are incorporated. The shape of the conventional head actuator 56 is such that it is symmetrical with respect to straight line C–C drawn through the center of a pivot 57 and the magnetic head 53. A head actuator with such a shape is also referred to as an in-line head actuator.
In the removable hard disk apparatus 51, the disk 52 is housed inside a disk cartridge 58, and is freely removable from the body of the apparatus. FIG. 12 is a sectional view showing a configuration example of the main portion of a conventional disk apparatus. In addition, FIG. 12 is a sectional view along line D—D in FIG. 11B.
In the in-line head actuator 56, as shown in FIGS. 11A and 11B, when the head actuator 56 is rotated to a point where the magnetic heads 53 reach the innermost portion of the disk 52, the tip of the arm 55 interferes with the disk 52. Therefore, in order to avoid this interference with the disk 52, the arm 55 is shaped, as shown in FIG. 12, such that its tip is bifurcated. Bosses 59 of the suspensions 54 are mounted on the tips of upper and lower blocks 55a and 55b of the bifurcated tips such that the tip portions of the bosses 59 face outward, and they are fixed in place through caulking or adhesion.
Therefore, in the conventional head actuator 56, because a certain thickness is necessary for each of the tip portions of the bifurcated arm 55 in order to maintain enough strength, the actuator 56 as a whole inevitably becomes thicker, and thus therein lies a problem in that it also becomes difficult to make the hard disk apparatus 51 equipped with this head actuator 56 thinner.
Further, with respect to a removable hard disk apparatus that uses the conventional head actuator 56, as shown in FIG. 12, along with the head actuator 56, the disk cartridge 58 inevitably becomes thicker as well. In other words, because the bifurcated tip portions of the arm 55 interfere with the disk 52 and the disk cartridge 58, it is difficult to make the disk cartridge 58, and thus the apparatus as a whole, thinner.
On the other hand, in recent years, as hard disk apparatuses are built into an increasing number of portable devices, there is a demand for thinner drive apparatuses, and thus it is desired that head actuators be made as thin as possible.
In addition, in the head actuator 56, in order to fix the suspension 54 onto the arm 55, ball caulking has been used conventionally. FIGS. 13A and 13B show an example of a conventional fixing process. In conventional methods of fixing the suspensions 54 in place by way of ball caulking, as shown in FIG. 13A, bosses 59 are positioned in each of the blocks 55a and 55b of the bifurcated arm 55 such that the tip portions of the bosses 59 face outward. Then, as shown in FIG. 13B, an intermediate support member 60 is positioned between the bifurcated arm 55, the arm 55 is held by and between support members 61a and 61b, and a caulking ball 62 (a steel ball), which is slightly larger than the diameter of the hole in the bosses 59 of the suspensions 54, is pressed thereinto and is made to pass therethrough. In so doing, by having the bosses 59 of the suspensions 54 stretched in the radial direction by the caulking ball 62, the suspension 54 is fixed to the arm 55.
However, in trying to make the conventional head actuator 56 thinner, because the tip portion of the arm 55 is bifurcated, the upper and lower blocks 55a and 55b lack strength (i.e. thickness), and deformation was easily caused by the caulking process. As the caulked portion gets deformed, the load with which the magnetic heads 53 are pressed against the disk 52 changes, an appropriate flying height cannot be secured, thereby causing problems in reading and recording signals.
Further, the conventional head actuator 56, during its manufacturing process, has to have the intermediate support member 60 inserted between the blocks 55a and 55b of the bifurcated arm 55. However, because the magnetoresistive head element of the magnetic heads 53 is sensitive to shock, dust, static electricity and the like, jigs such as this intermediate support member 60 have to be handled with great care so that they do not contact the magnetic heads 53, which hinders assembly efficiency during the caulking process, and there is a problem in that it is costly.
Meanwhile, a hard disk apparatus having a head actuator bent in the shape of an L is proposed (see patent document 1, for example).